87191961 has 4 divisors (see below), whose sum is σ = 116255952. Its totient is φ = 58127972.

The previous prime is 87191959. The next prime is 87191971. The reversal of 87191961 is 16919178.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 87191961 - 2¹ = 87191959 is a prime.

It is not an unprimeable number, because it can be changed into a prime (87191921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14531991 + ... + 14531996.

It is an arithmetic number, because the mean of its divisors is an integer number (29063988).

Almost surely, 2^87191961 is an apocalyptic number.

It is an amenable number.

87191961 is a deficient number, since it is larger than the sum of its proper divisors (29063991).

87191961 is a wasteful number, since it uses less digits than its factorization.

87191961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29063990.

The product of its digits is 27216, while the sum is 42.

The square root of 87191961 is about 9337.6635728645. The cubic root of 87191961 is about 443.4304186848.

The spelling of 87191961 in words is "eighty-seven million, one hundred ninety-one thousand, nine hundred sixty-one".